DSSR-PyMOL cartoon-block schematics: PDB entry 5fkw

PDB-id

5fkw; DSSR-derived features in text and JSON formats

Class

transferase

Method

cryo-EM (7.3 Å)

Summary

cryo-EM structure of the e. coli replicative DNA polymerase complex bound to DNA (DNA polymerase iii alpha, beta, epsilon)

Reference

Fernandez-Leiro R, Conrad J, Scheres SH, Lamers MH (2015): "cryo-EM structures of theE. colireplicative DNA polymerase reveal its dynamic interactions with the DNA sliding clamp, exonuclease andtau." Elife, 4. doi: 10.7554/eLife.11134.

Abstract

The replicative DNA polymerase PolIIIα from Escherichia coli is a uniquely fast and processive enzyme. For its activity it relies on the DNA sliding clamp β, the proofreading exonuclease ε and the C-terminal domain of the clamp loader subunit τ. Due to the dynamic nature of the four-protein complex it has long been refractory to structural characterization. Here we present the 8 Å resolution cryo-electron microscopy structures of DNA-bound and DNA-free states of the PolIII-clamp-exonuclease-τ_c complex. The structures show how the polymerase is tethered to the DNA through multiple contacts with the clamp and exonuclease. A novel contact between the polymerase and clamp is made in the DNA bound state, facilitated by a large movement of the polymerase tail domain and τ_c. These structures provide crucial insights into the organization of the catalytic core of the replisome and form an important step towards determining the structure of the complete holoenzyme.